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Chemistry_All_Challenging_Chapters_146_A&R_Test_Items_Clears_Misunderstanding
Chemistry All_Challenging_Chapters_146_A&R_Test_Items_Clears_Misunderstanding
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Spread the Happiness. Assertion and Reason Statements Feedback: 9008271516CHEMISTRY _ Chapter-wise A&R Items
S# Assertion Reason
Organic Chemistry - Some Basic Principles And Techniques
Alkanes exhibit tetrahedral geometry. sp³ hybridization of carbon atoms leads to four sp³ hybrid
1
orbitals with tetrahedral arrangement for σ bond formation.
IUPAC nomenclature prioritizes the longest This systematic approach ensures unique names for even
2 carbon chain and functional group location. complex molecules, considering both chain length and
functionality.
Homolytic bond cleavage in H yields two H⁰ Equal sharing of electrons in the H-H bond creates two
3
radicals. neutral hydrogen atoms with unpaired electrons each.
Structural isomers (e.g., pentane vs. 2- They have the same number of atoms (C H ) but distinct
methylbutane) share the same molecular arrangements of carbon atoms within the chain.
4
formula but differ in carbon chain connectivity.
Ammonia (NH ) acts as a nucleophile due to The electron-rich lone pair on nitrogen in NH can be
5 its lone pair of electrons. donated to an electron-deficient electrophile to form a new
bond.
The electron-withdrawing (-I effect) of a The electronegative chlorine pulls electron density towards
6 chlorine atom strengthens the C-H bond in itself, shortening and strengthening the C-H bond in CH Cl.
CH Cl compared to CH .
Carboxylic acids (RCOOH) are stronger acids The carboxylate anion (RCOO ) exhibits more effective
7 than phenols (ArOH) due to resonance delocalization of the negative charge compared to the
stabilization. phenoxide anion (ArO ), increasing its stability and acidity.
Benzene exhibits aromaticity due to its cyclic, The presence of a six-membered ring with alternating single
conjugated π-electron system following and double bonds (conjugated system) and 6 π electrons (4n
8
Hückel's rule (4n + 2 π electrons). + 2, where n = 1) satisfies the criteria for aromatic character,
resulting in unique stability.
Delocalization of π-electrons is resonance. Describes the spreading of π-electrons over several atoms,
9
contributing to stability.
Simple distillation cannot effectively separate While chloroform (61°C) and aniline (184°C) have
a mixture of chloroform and aniline. significantly different boiling points, simple distillation
10
cannot effectively separate them due to their azeotropic
behavior.
The hybridization of carbon in H C=O is sp² Three sp² hybrid orbitals form σ bonds with H atoms, and the
11 and shape is trigonal planar. unhybridized p orbital participates in the π bond with
oxygen, resulting in a trigonal planar geometry.
Substitution reactions of benzene are slower The aromatic stabilization provided by benzene's delocalized
than those of alkenes, despite both involving pi electron system makes it less reactive towards
pi bonds. electrophilic attack compared to alkenes, despite both
containing pi bonds.
Thermodynamics
Adiabatic compression of an ideal gas cools W > 0 (work done on the system) decreases internal energy
12 the system (ΔT < 0). (ΔU < 0), but heat transfer (Q) is zero, resulting in a net
temperature decrease.
The heat of neutralization (ΔH_neutral) for a The dominant factor is the formation of water (ΔH⁰f of water
13 strong acid-strong base reaction is nearly is constant), regardless of the specific strong acid and
constant. strong base used.
Diamond can be converted to graphite at At equilibrium, the forward and reverse reactions occur at
14
standard pressure and temperature (ΔG = 0). the same rate, with no net change in free energy.
For a reaction at equilibrium, the equilibrium K is a ratio of products and reactants raised to their
15 constant (K) depends only on temperature (T). stoichiometric coefficients, and temperature affects reaction
rates to reach equilibrium.
∆S⁰ (standard entropy change) of vaporization The transition from liquid (ordered) to gas (disordered)
16
is always positive. molecules leads to a significant increase in entropy.
The efficiency (η) of a Carnot cycle is higher Carnot cycle is a reversible cycle, representing the
17 than that of any other heat engine operating theoretical maximum efficiency achievable for a given
between the same hot and cold reservoirs. temperature difference.
ΔG⁰ for a non-spontaneous reaction is always A positive ΔG⁰ indicates the reaction is not favorable under
18 positive. standard conditions; however, coupled reactions or
changing conditions can affect spontaneity.
The ideal gas law (PV = nRT) can be derived It relates pressure (P), volume (V), temperature (T), and
19 from kinetic molecular theory. moles (n) based on the assumptions of ideal gas behavior
(collisions, negligible interactions).
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, Spread the Happiness. Assertion and Reason Statements Feedback: 9008271516
CHEMISTRY _ Chapter-wise A&R Items
S# Assertion Reason
The heat capacity of a mixture (C_mix) can be C_mix = Σ(w_i * C_i); weighted average based on the amount
calculated from the heat capacities of its of each component in the mixture.
20
components (C_i) and their mass fractions
(w_i).
Bond enthalpies can be used to estimate the Bond enthalpies represent the average energy required to
21 enthalpy change (ΔH) for breaking and break a specific bond type, and their sum can be used in
forming bonds in a reaction. calculations considering stoichiometry.
The Clausius-Clapeyron equation relates It describes the equilibrium condition between a liquid and
22 pressure, temperature, and enthalpy of its vapor and how these factors influence vapor pressure.
vaporization (ΔH_vap) for phase transitions.
For a spontaneous reaction at constant ΔG = ΔH - TΔS; a negative ΔG indicates the process
temperature and pressure (ΔT = 0, ΔP = 0), the proceeds spontaneously under these conditions.
23
change in Gibbs free energy (ΔG) is negative
(ΔG < 0).
Adding heat to ice at 0°C increases its Despite being at its melting point, heat energy increases
temperature. ice's temperature until it completely melts, due to latent heat
absorption for phase change.
Solutions
Adding a non-volatile solute elevates solvent's Disrupts solvent-solvent interactions, requiring higher
24 boiling point (boiling point elevation). temperature for sufficient vapor pressure (ΔTb = Kb.m)
Colligative properties depend on solute Arise from the presence of solute particles affecting solvent-
25 particle concentration (not identity) in dilute solute interactions, independent of solute type (in dilute
solutions. solutions).
Gas solubility in a liquid decreases with Higher temperature increases gas molecule kinetic energy,
26
increasing temperature. making escape from the liquid more likely.
Ideal binary solutions follow Raoult's Law No solute-solvent interactions, solution behaves ideally with
27
(Pi = Xi * Po^i). partial pressure proportional to mole fraction.
Azeotropes (binary mixtures) have a constant Specific interactions (e.g., hydrogen bonding) cause boiling
28 boiling point and resist separation by simple point minimum/maximum, hindering separation at constant
distillation. pressure.
Osmosis occurs when a semi-permeable Net solvent movement from low solute concentration (high
29 membrane separates solutions with different water potential) to high solute concentration (low water
solute concentrations. potential) to reach equilibrium.
Evaporation rate of a liquid increases with More surface area allows more molecules to escape into the
30
increasing surface area exposed to air. vapor phase per unit time (kinetic theory).
Gas solubility in a liquid is directly Higher gas pressure increases gas molecule concentration
31 proportional to the gas's partial pressure at the liquid surface, leading to higher dissolved gas
(Henry's Law: C = kH). concentration.
Adding sugar (a non-volatile solute) to coffee Disrupts water molecule interactions, reducing free solvent
32 lowers its freezing point (freezing point molecules for ice crystal formation (ΔTf = Kf .m )
depression).
Concentrated solutions have higher osmotic Requires greater pressure to prevent solvent movement
33 pressure compared to dilute solutions. across a semi-permeable membrane due to higher solute
concentration difference.
Van't Hoff factor (i) accounts for the number of Dissociation increases effective solute particles (i times
34 solute particles produced during dissociation. greater than formula units), affecting colligative properties.
Colligative properties depend on the nature of The extent of interaction (e.g., dipole-dipole) can influence
35
the solute and solvent interaction. the degree of colligative property change.
Increasing the concentration of a solute in a Solute particles interfere with the formation of a solvent's
solution can decrease its freezing point. crystal lattice, requiring a lower temperature for freezing.
Some Basic Concepts Of Chemistry
The number of molecules in a mole of any 1 mole represents a specific amount of particles (6.023 x
36 substance is constant (Avogadro's Constant). 10^23), ensuring a consistent number of molecules
regardless of the substance.
Empirical and molecular formulas differ in the The empirical formula shows the simplest whole number
37 level of detail regarding atom ratios in a ratio of atoms, while the molecular formula specifies the
compound. exact number of each atom present.
The limiting reagent in a reaction dictates the The limiting reagent is entirely consumed, limiting the
38 maximum amount of product formed. product formation based on its stoichiometric ratio with the
limiting reagent in a balanced chemical equation.
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